Intraocular lenses having zone-by-zone step height control

ABSTRACT

A method and system provide an ophthalmic device. The ophthalmic device includes an ophthalmic lens having anterior surface, a posterior surface and at least one diffractive structure including a plurality of zones. The at least one diffractive structure is for at least one of the anterior surface and the posterior surface. Each zone includes at least one echelette having a least one step height. The step height(s) are individually optimized for each zone. To compensate chromatic aberration of eye from distance to a range of vision, a greater than 2π phase step height may be employed and the step height(s) folded by a phase, which is an integer multiple of two multiplied by π. Hence chromatic aberration of eye may be compensated to improve vision from distance to near.

FIELD

The present disclosure relates generally to intraocular lenses and moreparticularly to intraocular lenses having zone by zone step heightcontrol.

BACKGROUND

Intraocular lenses (IOLs) are implanted in patients' eyes either toreplace a patient's lens or to complement the patient's lens. The IOLmay be implanted in place of the patient's lens during cataract surgery.Alternatively, an IOL may be implanted in a patient's eye to augment theoptical power of the patient's own lens.

Some conventional IOLs are single focal length IOLs, while others aremultifocal IOLs. Single focal length IOLs have a single focal length orsingle power. Objects at the focal length from the eye/IOL are in focus,while objects nearer or further away may be out of focus. Althoughobjects are in perfect focus only at the focal length, objects withinthe depth of focus (within a particular distance of the focal length)are still acceptably in focus for the patient to consider the objects infocus. Multifocal IOLs have at least two focal lengths. For example, abifocal IOL has two focal lengths for improving focus in two ranges: adistance focus corresponding to a larger focal length and a near focuscorresponding to a smaller focal length. Thus, a patient's distancevision and near vision may be improved. Trifocal IOLs have threefocuses: a far focus for distance vision, a near focus for near visionand an intermediate focus for intermediate vision. The intermediatefocus has an intermediate focal length between that of the near and farfocuses. Multifocal IOLs may improve the patient's ability to focus ondistant and nearby objects.

In order to fabricate a conventional IOL, optical design software isgenerally employed. The desired focal lengths and locations of zones onthe lens surface are provided. Given these inputs, the entire lens isanalytically optimized using the optical software. Stated differently,the diffraction structures for multiple zones are simultaneouslyoptimized using analytic tools. As a result, an IOL may be provided.

Although useful in addressing optical conditions, IOLs may suffer fromvarious drawbacks such as longitudinal chromatic aberration and/or alimited depth of focus. Different colors of light have differentwavelengths and, therefore, different frequencies. As a result, the IOLfocuses light of different colors at different distances from the lens.The IOL may be unable to focus light of different colors at thepatient's retina. The polychromatic image contrast for the IOL may beadversely affected. In addition, the depth of focus of the IOL may notbe as large as desired. The patient's vision for ranges further from thefocal length may be adversely affected. Consequently, an extended depthof focus (EDOF) may be desired.

Accordingly, what is needed is a system and method for improving IOLs.

SUMMARY

A method and system provide an ophthalmic device. The ophthalmic deviceincludes an ophthalmic lens having anterior surface, a posterior surfaceand at least one diffractive structure including a plurality of zones.The at least one diffractive structure is for at least one of theanterior surface and the posterior surface. Each zone includes at leastone echelette having a least one step height. The step height(s) areindividually provided for each zone. The at least one step height isalso folded by a phase, which is an integer multiple of two multipliedby π.

The lens may having the diffractive structure(s) described above mayhave reduced chromatic aberration and greater EDOF. As a result,performance may be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and theadvantages thereof, reference is now made to the following descriptiontaken in conjunction with the accompanying drawings in which likereference numerals indicate like features and wherein:

FIGS. 1A and 1B depict a plan and side views of an exemplary embodimentof a multifocal ophthalmic device that includes individually optimizedzones and phase folding;

FIG. 2 depicts an exemplary embodiment of a sag profile for adiffractive structure of a multifocal ophthalmic lens that includesindividually optimized zones and phase folding.

FIGS. 3A-3B depict exemplary embodiments of the intensity versus focusshift for a multifocal ophthalmic lens that includes individuallyoptimized zones and phase folding;

FIG. 4 depicts an exemplary embodiment of sag profile for a diffractivestructure of an ophthalmic lens having an extended depth of focus andthat includes individually optimized zones and phase folding;

FIGS. 5A-5B depict exemplary embodiments of the intensity versus focusshift a lens that includes individually optimized zones and phasefolding;

FIG. 6 is flow chart depicting an exemplary embodiment of a method forfabricating an ophthalmic device that includes individually optimizedzones and phase folding;

FIG. 7 depicts an exemplary embodiment of a sag profile for diffractivestructure during design that includes individually optimized zones;

FIG. 8 depicts an exemplary embodiment of a sag profile for diffractivestructure during design that includes individually optimized zones andphase folding; and

FIG. 9 is flow chart depicting an exemplary embodiment of a method forutilizing an ophthalmic device including a multifocal lens that may havereduced chromatic aberration.

DETAILED DESCRIPTION

The exemplary embodiments relate to ophthalmic devices such as IOLs andcontact lenses. The following description is presented to enable one ofordinary skill in the art to make and use the invention and is providedin the context of a patent application and its requirements. Variousmodifications to the exemplary embodiments and the generic principlesand features described herein will be readily apparent. The exemplaryembodiments are mainly described in terms of particular methods andsystems provided in particular implementations. However, the methods andsystems will operate effectively in other implementations. For example,the method and system are described primarily in terms of IOLs. However,the method and system may be used with contact lenses. Phrases such as“exemplary embodiment”, “one embodiment” and “another embodiment” mayrefer to the same or different embodiments as well as to multipleembodiments. The embodiments will be described with respect to systemsand/or devices having certain components. However, the systems and/ordevices may include more or less components than those shown, andvariations in the arrangement and type of the components may be madewithout departing from the scope of the invention. The exemplaryembodiments will also be described in the context of particular methodshaving certain steps. However, the method and system operate effectivelyfor other methods having different and/or additional steps and steps indifferent orders that are not inconsistent with the exemplaryembodiments. Thus, the present invention is not intended to be limitedto the embodiments shown, but is to be accorded the widest scopeconsistent with the principles and features described herein.

A method and system provide an ophthalmic device. The ophthalmic deviceincludes an ophthalmic lens having anterior surface, a posterior surfaceand at least one diffractive structure including a plurality of zones.The diffractive structure(s) are for at least one of the anteriorsurface and the posterior surface. Each zone includes at least oneechelette having a least one step height. The step height(s) areindividually determined for each zone. The step height(s) are alsofolded by a phase, which is an integer multiple of two multiplied by π.

FIGS. 1A-1B depict an exemplary embodiment of an ophthalmic device 100that may be used as an IOL. FIG. 1A depicts a plan view of theophthalmic device 100, while FIG. 1B depicts a side view of theophthalmic lens 110. For clarity, FIGS. 1A and 1B are not to scale, forexplanatory purposes only and depict only some features. The ophthalmicdevice 100 includes an ophthalmic lens 110 (herein after “lens”) as wellas haptics 102 and 104. The lens 110 may be made of a variety of opticalmaterials including but not limited to one or more of silicone, ahydrogel, an acrylic and AcrySof®. Haptics 102 and 104 are used to holdthe ophthalmic device 100 in place in a patient's eye (not explicitlyshown). In other embodiments, other mechanism(s) might be used to retainthe ophthalmic device in position in the eye. Thus, the haptics 102and/or 104 might be omitted. For clarity, the haptics are not depictedin the remaining drawings. Although the lens 110 is depicted as having acircular cross section in the plan view of FIG. 1A, in otherembodiments, other shapes may be used. Although described in the contextof an IOL, the lens 110 may be a contact lens. In such a case, thehaptics 102 would be omitted and the lens 110 sized and otherwiseconfigured to reside on the surface of the eye.

The lens 110 may, but need not, be a multifocal lens. The lens 110 hasan anterior surface 112 a posterior surface 114 and an optic axis 116.The lens is also characterized by a diffractive structure 120 and a basecurvature 121. The lens 110 may provide a base power, astigmatismcorrection and/or other vision correction(s). The lens 110 may beaspheric and/or toroidal, have the same or different base curvatures onthe surfaces 112 and 114 and/or other characteristics that are not shownor discussed in detail for simplicity. Although one diffractivestructure 120 is shown on the anterior surface 112, the diffractivestructure 120 might be located on the posterior surface 114. In stillother embodiments, diffractive structures may be located on the anteriorsurface 112 and the posterior surface 114. Such diffractive structuresmay be the same or different. The diffractive structure 120 may, butneed not, be partial aperture diffractive structure. Further, althoughshown as a physical diffractive structure, in other embodiments, thediffractive structure 120 may be formed by a change in the index ofrefraction of the lens 110.

The diffractive structure 120 may provide a single focal length ormultiple focal lengths. In some embodiments, the diffractive structure120 is used to provide a bifocal (two focal lengths for near anddistance vision) lens 110. In other embodiments, the diffractivestructure 120 may provide a trifocal (three focal lengths for near,intermediate and distance vision) lens 110. A quadrifocal or othermultifocal lens might also be provided. The diffractive structure 120may be configured for particular wavelength(s). For example, differentzones 111 of the diffractive structure 120 may be configured for lightof different wavelengths. Alternatively, the diffractive structure 120may be designed for light of a single wavelength.

The diffractive structure 120 includes multiple zones 122A, 122B and122C (collectively zones 122) corresponding to different ranges indistance perpendicular to the optic axis 116 (i.e. different radii).Although three zones 122 are shown, the lens 110 may have another numberof zones. A zone 122A, 122B and/or 122C is a circle or an annular ringalong the surface from a minimum radius to a maximum radius from theoptic axis 116. For example, in some embodiments, the diffractivestructure 120 may have ring diameters for the zones 122 set by theFresnel diffractive lens criteria. Alternatively, other criteria may beused to determine the size and location of each of the zones 122.

Each of the zones 122 includes steps, or echelettes 124. The echelettes124 have step heights that correspond to phase differences. The stepheight of an echelette 124 is the physical step height (h) multiplied bythe difference in index of refraction between the lens 110 and thesurrounding media (Δn). In other words, the step height=h·Δn. The phasedifference, ϕ, for an echelette 124 is proportional to the step heightdivided by the wavelength, λ. More specifically, ϕ=(2·π·h·Δn)/λ. A phasedifference of 2π thus corresponds to one wavelength in step height.Thus, the terms step height and phase are considered to be effectivelysynonymous herein.

The echelettes 124 of one or more of the zones 122 are individuallyoptimized. Stated differently, one or more of the characteristics of theechelettes 124 for a zone 122A, 122B and/or 122C are determined for thatzone 122A, 122B and/or 122C, respectively, independent of thecharacteristics of the echelettes 124 in another zone. In someembodiments, the step heights (phases) of the echelettes 124 in thezones 122 are separately determined on a zone-by-zone basis. Thus, thestep height(s) for each zone 122A, 122B and/or 122C are determinedindependently of the step height(s) for another zone. In otherembodiments, additional or other characteristics of the echelettes 124may be separately configured on a zone-by-zone basis. For example, thespacing between echelettes 124 may also be independently controlled foreach zone 122.

The characteristic(s) of the echelettes 124 for each of the zones 122A,122B and 122C may be independently optimized based on selected criteria.For example, particular focal length(s) for the lens 110, target focuspositions, location and amount of constructive interference, targetphases and/or other criteria may be used to separately determine thestep height(s) for each of the zones 122. These criteria may changebetween the zones 122. In other embodiments, these criteria may be thesame for each of the zones 122. Because of the locations of the zones122 differ, different step heights may be determined for different zones122 even if the criteria stay the same.

In some embodiments, the phases (i.e. step heights) for the echelettes124 in each zone can be individually optimized such that each of thezones 122 constructively interferes at different target positions. As aresult, the depth of focus may be improved for the lens 110. In someinstances, a relatively uniform through-focus may be achieved. Each ofthe zones 122 may be separately optimized for one or more of the focallengths of a multifocal lens 110. For example, each of the zones 122 maybe optimized to provide different intermediate focal lengths. Thus, thedepth of focus may be improved.

Although discussed in the context of independently configuring theechelettes 124 for each of the zones 122, one of ordinary skill in theart will recognize that not all of the zones 122 must be so configured.For example, in some embodiments, echelettes 124 for only the zones 122Aand 122B might be separately determined. In other embodiments,echelettes 124 for only the zones 122A and 122C may be separatelyconfigured. In still other embodiments, characteristics of theechelettes 124 for only the zones 122B and 122C might be independentlydetermined. In other embodiments, all of the zones 122 of the lens 110might be separately manipulated. Thus, the specific zones 122 havingechelettes 124 that are independently manipulated may change betweenembodiments.

The zones 122 may undergo phase folding in addition to separate,zone-by-zone optimization of the step height(s). The individuallydetermined step height(s) for one or more of the zones 122 may be large.The corresponding phases may exceed 2·π. In some cases, the optimizedstep heights may correspond to phases of at least 3·π, at least 4·π, ormore. Therefore, the step heights are folded by a phase of 2·π·n, wheren is a positive integer, if the step height is sufficiently large. Insome embodiments, the step heights of the echelettes 124 may be reducedto provide a maximum phase of 2·π. Thus, in addition to being separatelycontrolled, the step heights of the echelettes 124 of each zone 122A,122B and/or 122C are folded. This reduction in the step height mayreduce the light interference from light far from the optic axis 116.The phase folding may also provide a negative dispersion that maypartially or wholly compensate for the positive dispersion of thematerial from which the lens 110 is formed.

The ophthalmic lens 110 may have improved performance. The ophthalmiclens 110 may be a multifocal lens. The ophthalmic device 100 may be usedto treat conditions such as presbyopia. Other conditions such asastigmatism may be treated and performance of the lens 110 may beimproved through the use of the base curvature 121, asphericity of thelens 110, toricity of the lens 110, apodization of the echelettes 122and other characteristics of the lens. In addition, the lens 110 mayhave improved EDOF as well as reduced chromatic aberration. Separatelycontrolling the step height(s) of the echelettes 124 in each of thezones 122 may allow the image to be sufficiently in focus over a largerrange of distances. Thus, depth of focus may be improved. Because theechelettes are also phase folded, chromatic aberrations introduced bythe lens 110 may be compensated for. This use of the superzone and phasewrapping may compensate a chromatic aberration of the eye through strongnegative dispersion of a diffractive lens and correcting chromaticaberration from distance to a range of vision. Thus, depth of focus maybe increased while a more achromatic lens 110 may be provided.Consequently, performance may be improved.

The benefits of the ophthalmic lens 110 may be better understood withrespect to certain embodiments. FIG. 2 depicts a sag profile 130 foranother exemplary embodiment of a diffractive structure that includesindividually controlled zones and phase folding. Thus, the sag profile130 and diffractive structure 130 are referred to interchangeably. Thediffractive structure 130 may take the place of the diffractivestructure 120 in the lens 110. The sag profile 130 indicates that thereare zones 134, 136 and 138, each of which includes one or moreechelettes 132. FIGS. 3A and 3B are graphs 140 and 150, respectively,depicting exemplary embodiments of the monochromatic and photopicintensity, respectively, versus focus shift for a trifocal lens 110 madewith the diffractive structure 130. The curves 142 and 152 are for oneset of line pairs, while the curves 144 and 154 are for another set ofline pairs having twice the frequency. FIGS. 2-3B are not to scale andfor explanatory purposes only.

As can be seen in the graphs 140 and 150, the thru focus modulationtransfer function (MTF) curves 142/152 and 144/154 are shifted due toseparate, zone-by-zone control of the step heights of the echelettes 132in the sag profile 130. This shift compensates for valleys in the MTFcurves. Thus, the depth of focus for a lens incorporating the sagprofile 130 has been improved. Because of phase folding of thediffractive structure 130, chromatic aberration may also be compensatedfor. As a result, the MTF is shown as dropping by a smaller amount overthe extended distance in the graphs 140 and 150. Thus, the depth offocus and achromatization of the lens 110 having the sag profile 130 maybe improved. The performance of the lens 110 employing a diffractivestructure having the sag profile 130 may be enhanced.

FIG. 4 depicts a sag profile 130′ for another exemplary embodiment of adiffractive that includes individually controlled zones and phasefolding. Thus, the sag profile 130′ and diffractive structure 130′ arereferred to interchangeably. The diffractive structure 130′ may take theplace of the diffractive structure 120 in the lens 110. The sag profile130′ indicates that there are zones 134′, 136′ and 138′, each of whichincludes one or more echelettes 132′. FIGS. 5A and 5B are graphs 140′and 150′, respectively, depicting exemplary embodiments of MTF versusfocus shift for a trifocal lens 110 made with the diffractive structure130′. The curve 142′ depicts the monochromatic MTF, while the curve 152′is for photopic MTF. FIGS. 4-5B are not to scale and for explanatorypurposes only. In the embodiment shown, the near power may be set byadding power to the lens 110, while the intermediate power may beprovided by separate, zone-by-zone optimization of the step heights forthe sag profile 130′. In addition, the step height for the echelettes132′ may be folded by an integer multiple of 2·π. For example, themaximum phase corresponding to the echelettes 132′ may be 2·π.

As can be seen in the graphs 140′ and 150′, the curves 142′ and 152′provide for an intermediate focus. This is due to separate control ofthe echelette step heights for the zones 134′, 136′ and 138′ as shown inthe sag profile 130′. Thus, the depth of focus has been improved.Because of phase folding of the diffractive structure 130′, chromaticaberration may also be compensated for the depth of focus andachromatization of the lens 110 having the sag profile 130′ may beimproved. Thus performance of the lens 110 employing a diffractivestructure having the sag profile 130 may be enhanced.

FIG. 6 is an exemplary embodiment of a method 200 for providing amultifocal diffractive lens having reduced chromatic aberration. Forsimplicity, some steps may be omitted, interleaved, and/or combined.FIGS. 7 and 8 depict sag profiles 170 and 170′ for a lens designed usingthe method 200. The sag profiles 170 and 170′ are for explanatorypurposes only and are not intended to represent specific devices.Referring to FIGS. 6-8, the method 200 may be used to provide theophthalmic device 100 and lens 110 and diffractive structure 120.However, the method 200 may be used with one or more other diffractivestructure 130 and/or 130″ and/or an analogous ophthalmic device.

The method 200 may be executed using a system including one or moreprocessors and a memory. The one or more processors may be configured toexecute instructions stored in the memory to cause and control some orall of the process(es) set forth in the drawings and described herein.As used herein, a processor may include one or more microprocessors,field-programmable gate arrays (FPGAs), controllers, or any othersuitable computing devices or resources, and memory may take the form ofvolatile or non-volatile memory including, without limitation, magneticmedia, optical media, random access memory (RAM), read-only memory(ROM), removable media, or any other suitable memory component. Memorymay store instructions for programs and algorithms that, when executedby a processor, implement the functionality described herein withrespect to any such processor, memory, or component that includesprocessing functionality. Further, aspects of the method and system maytake the form of an entirely hardware embodiment, an entirely softwareembodiment (including firmware, resident software, micro-code, etc.) oran embodiment combining software and hardware aspects. Furthermore,aspects of the method and system may take the form of a softwarecomponent(s) executed on at least one processor and which may beembodied in one or more computer readable medium(s) having computerreadable program code embodied thereon.

The diffractive structure for the lens 110 is designed using steps 202and 204. The step height(s) for the echelettes are determined byindividually configuring each of the zones, via step 202. Step 202 maybe performed analytically, using processor(s) that executesinstructions. For example, the desired target focus locations, focallengths, zone locations and/or other criteria may be provided as inputsto software for designing optical gratings and an optimizationperformed. As a result, optimized step heights that correspond tooptimized phases are independently determined for each zone of some orall of the diffractive structure being formed. Although termed anoptimization process, one of ordinary skill in the art will recognizethat the step height(s) determined may not be optimal for every possibleset of criteria used. Instead, the optimization process is one that canuse analytic tools to determine the step height based on criteriaprovided by the user. FIG. 7 is a graph 170 depicting a simplified,superzone sag profile 172 resulting from step 202. The profile 172 issimplified as a linear profile but more generally would be curved. Thus,the sag profile 172 has three zones. The optimization process hasresulted in echelettes for the sag profile 172 having large optimizedstep heights. The sag profile 172 includes first and second orders asthe main orders. For comparison, a sag profile 174 for a monofocalFresnel lens and a sag profile 176 for a bifocal diffractive lens areshown. The sag profile 174 utilizes the first order, while the sagprofile 176 utilizes the zeroth and first orders. The phasescorresponding to the echelettes of the sag profile 172 have optimizedphases that are greater than 2·π.

The optimized step heights are folded if the optimized phases exceed2·π, via step 204. The phase used in folding is a positive integermultiplied by 2·π. In the embodiment shown, all of the zones have largeoptimized step heights. Consequently, the optimized step heights for allzones are folded. In another embodiment, the optimized step height foronly some zones may be folded. FIG. 8 is a graph 170′ depicting theresultant simplified sag profile 172′ after folding has been performed.The profile 172′ is simplified as a linear profile but more generallywould be curved. Thus, the echelettes of the sag profile 172′ all havereduced phases. Also shown with dashed lines is the original curve 172and the direction the sag profile 172 is moved to form the final curve172′.

The lens(es) 110 are fabricated, via step 206. Thus, the desireddiffractive structure 120 having the sag profile 170′ may be formed. Thediffractive structure(s) 120, 130, 130′ and/or an analogous diffractivestructure may be provided and the benefits thereof achieved.

FIG. 9 is an exemplary embodiment of a method 210 for treating anophthalmic condition in a patient. For simplicity, some steps may beomitted, interleaved, and/or combined. The method 210 is also describedin the context of using the ophthalmic device 100 and ophthalmic lens110. However, the method 210 may be used with one or more of diffractivestructures 130, 130′, 170′ and/or an analogous diffractive structure.

An ophthalmic device 100 for implantation in an eye of the patient isselected, via step 212. The ophthalmic device 100 includes an ophthalmiclens 110 having a diffractive structure 120 that has individuallyoptimized zones 122 that have also been folded. A lens having adiffractive structure 120, 130, 130′, 170′ and/or an analogousdiffractive structure may thus be selected for use.

The ophthalmic device 100 is implanted in the patient's eye, via step204. Step 204 may include replacing the patient's own lens with theophthalmic device 100 or augmenting the patient's lens with theophthalmic device. Treatment of the patient may then be completed. Insome embodiments implantation in the patient's other eye of anotheranalogous ophthalmic device may be carried out.

Using the method 200, the diffractive structure 120, 130, 130′, 170′and/or analogous diffractive structure may be used. Thus, the benefitsof one or more of the ophthalmic lens 110 may be achieved.

A method and system for providing an ophthalmic device have beendescribed. The method and systems have been described in accordance withthe exemplary embodiments shown, and one of ordinary skill in the artwill readily recognize that there could be variations to theembodiments, and any variations would be within the spirit and scope ofthe method and system. Accordingly, many modifications may be made byone of ordinary skill in the art without departing from the spirit andscope of the appended claims.

We claim:
 1. An ophthalmic lens having at least one focal length, theophthalmic lens comprising: an anterior surface; a posterior surface;and at least one diffractive structure including a plurality of zones,each of the plurality of zones including at least one echelette havingat least one step height, the at least one diffractive structure beingfor at least one of the anterior surface and the posterior surface, theat least one step height being individually determined for each zone ofthe plurality of zones, the at least one step height being folded by aphase, the phase being an integer multiple of two multiplied by 7C. 2.The ophthalmic lens of claim 1 wherein the at least one focal lengthincludes a plurality of focal lengths such that the ophthalmic lens is amultifocal lens.
 3. The ophthalmic lens of claim 2 wherein the each zoneis individually optimized for a portion of the plurality of focallengths.
 4. The ophthalmic lens of claim 2 wherein the each zone isindividually optimized for the plurality of focal lengths.
 5. Themultifocal ophthalmic lens of claim 1 wherein the at least one stepheight includes a plurality of step heights.
 6. The ophthalmic lens ofclaim 1 wherein the at least one step height is not more than twomultiplied by π.
 7. The ophthalmic lens of claim 1 wherein the at leastone diffractive structure is incorporated into the anterior surface. 8.The ophthalmic lens of claim 1 wherein the at least one diffractivestructure is incorporated into the posterior surface.
 9. The ophthalmiclens of claim 1 wherein the ophthalmic lens is selected from anintraocular lens and a contact lens.
 10. The ophthalmic lens of claim 1wherein the each zone is individually optimized for a plurality oftarget positions.
 11. A multifocal ophthalmic device comprising: anophthalmic lens including an anterior surface, a posterior surface, andat least one diffractive structure including a plurality of zones, eachof the plurality of zones including at least one echelette having atleast one step height, the at least one diffractive structure being forat least one of the anterior surface and the posterior surface, the atleast one step height being individually determined for each zone of theplurality of zones, the at least one step height being folded by aphase, the phase being an integer multiple of two multiplied by π; and aplurality of haptics coupled with the ophthalmic lens.
 12. A method forfabricating an ophthalmic lens having at least one focal length, themethod comprising: designing at least one diffractive structureincluding a plurality of zones for incorporation into at least one of ananterior surface and a posterior surface, each of the plurality of zonesincluding at least one echelette having at least one step height, thestep of designing the at least one diffractive structure furtherincluding individually optimizing each zone of the plurality of zones toprovide at least one optimized step height having at least one optimizedphase; and folding the at least one optimized step height by a phase toprovide the at least one step height if the optimized step phase exceedstwo multiplied by π, the phase being an integer multiple of twomultiplied by π; and fabricating the ophthalmic lens using the at leastone step height for the at least one diffractive structure.
 13. Themethod of claim 12 wherein the at least one focal length is a pluralityof focal lengths and wherein the step of individually optimizing eachzone further includes individually optimizing each zone for at least aportion of the plurality of focal lengths.
 14. The method of claim 12wherein the at least one step height is not more than two multiplied byπ.
 15. The method of claim 12 wherein the at least one diffractivestructure is incorporated into the anterior surface.
 16. The method ofclaim 12 wherein the at least one diffractive structure is incorporatedinto the posterior surface.
 17. The method of claim 12 wherein the stepof individually optimizing each zone further includes individuallyoptimizing each zone for a plurality of target positions.